Electrical problems with 2001 Rodeo

[hroark7]

Hey all - new to the forum. I just got a 2001 Rodeo from a used car lot with no warranty and it developed the following problems about a day after I took it home:

1. Key reminder would buzz whenever the driver's side door was open (whether the keys or lights were on or not). Radio (6-Cd changer) would have buttons that would randomly not work. Taillights and license plate lights stayed on continuously.

I checked the fuse box on the driver's side interior compartment. No blown fuses, but found out that the "Audio +B" circuit had continuity across it (was passing 12.8 V to ground when I had a voltmeter hooked up to it). I traced the wires from the back of the fuse box to behind the dash for the radio, and a black connector near the dead pedal. Circumvented those line with another wire and put that into the radio and the connector. Radio worked, key reminder started working like normal, tail lights started acting like normal.

2. The radio started acting funny whenever the car was stopped at an intersection, but would work like normal while I was driving. After some investigation, I discovered it was acting up whenever I had my foot on the brake. I also found out that the radio was acting up whenever I had my headlights on. I checked the fuse box again, found out that there were three other circuits that were grounding out - the radio was still grounding out, the dome light circuit, the power door lock circuit and the tail light/illumination circuit.

3.) After tearing out the kick panels, all of the plastics covering the wire bundle leading from the front of the car all the way to the taillights, unplugging, checking the ECU in the engine bay, checking all the fuses under the hood and unwrapping, checking all the wires leading from the fuse box and the steering column, I still have found only two places where there could have been a possible short and fixed them both...but the problem persists.

Any ideas on what the problem could be? I also checked my grounds today and they have continuity with the battery. The battery is brand new - I replaced it last week with a platinum series battery from advance auto.

I looked at what common problems there are with electronics on the rodeo, checked the tow hitch and it's not plugged into anything (has a watertight cap on it).

When I say the radio is acting funny - there are about 6 buttons that do not work on it when the headlights or taillights are active.

I love this car, but it would be a lot nicer if the radio would work. Thanks for the help -

[surferfletch]

Wacky things happen when these alternators start to fail. Do you have the original?

[hroark7]

UPDATE:

So I started eliminating possibilities - I disconnected components at various areas to make sure my short wasn't in those areas - sucks to work from the outside in towards the dash, but that's my only option.

I disconnected each component, turned on the radio, turned on the light switch, and the radio still acted funny in each case.

The areas eliminated were:

- The tail lights from the last black connector to the light
- The headlights and turn signal lights, from the fuse box to the lights
- The grounding points in the engine bay and at the alternator (exact same throughput and resistance as terminal-to-terminal on the battery)
- The black connector by the dead pedal
- The alternator, since my car is doing this while the engine is on or off

I rewired my radio back to stock, since it seems that was not the only shorted-out line.

so I'm now at the point that I know the radio system shorts out if I turn the light switch on, whether or not any lights are actually connected. If I disconnect the light switch, the whole system runs fine...except I have no lights for when it gets dark

Oh yeah, and my dash lights aren't working either. The bulbs don't look blown, but they do look smoky at the top - I'm going to buy a new pack and switch them just in case.

Any help is appreciated...

[amigo-2k]

So someone hacked the factory radio harness?

If so, I would toss the factory 6 disk (ebay it for 150) and buy a metra wireharness adapter and a new single disk player (maybe even one that plays MP3's).

The only other electrical gremlin to check is the trailer wireing harness. Unplug it from the truck (it is located in one of the jack bin type of area) and see what happens.

[hroark7]

I would love to chuck the 6-disk changer, I've got an MP3 player in my eclipse and it would my CD case a little more transportable between the two cars...I'm just worried that this short will ruin a new deck that I put in there.

So I traced the problem directly to the source - the tail light control wire

If I remove the tail light relay or the tail light fuse from the in-cabin fuse box, and turn the light switch on, there are no problems...so I can either drive without tail lights or no music, or try switching out my CD player, or keep trying to find this short...which I have just about given up on.

In case anybody else is diagnosing a problem like this - the tail light has two wires - some red/black with double silver dots coming from the fuse and to the relay, and some green/red with silver dots going into/coming out of the relay. The green/red wire is also an input to the radio, and is along the line to the 4wd button and the cruise control button. The wire normally has a resistance value of about .08 ohms and no voltage across it. When the lights are switched on, the wire is charged with an approximately 12.8 V signal. I'm thinking it's the way the radio is processing this 12.8V signal that's killing it. Either way,if I figure out an alternative way to fix it, or if the short or whatever problem it is ends up breaking something else, I'll let you all know.

[rodeo02]

You probably tried it already, but did you swap out the taillight relay with another known working relay? Bad relays can keep circuits live when they shouldn't be. Something to try if you cannot find any broken insulation/wires.
G/luck
Joel

[hroark7]

I already swapped the relay out - the new one worked the same way. I took apart the clock to find out what four signals it has input into it - it has two illumination wires (red/green I- wire and green/red I+ wire), battery (red/white) and ground (black/silver) connection. After looking at the wiring schematics, this all checks out. I was able to get the dash lights to work the inverse of how they are supposed to (dash lights on when light switch is on, off when the light switch is on) and the keyminder was buzzing.

The battery and ground are working as advertised - the ground is always 0 resistance with a known good ground, the battery is always putting out a constant +12 V. The I+ wire puts out 0 V when the lights are off, then puts out +12V when I switch the lights on - sounds about right. The I- wire (red/green) does the same thing. I'm thinking that maybe the I- wire is supposed to put out a -12V signal? Any ideas? I tried to ground the I- signal coming from the clock, and that only resulted in sparks at the clock connection. I'm thinking that may have messed up the connection, because I can't get the dash to light up anymore, even in the inverse fashion. Maybe my clock was blown to begin with?

I guess the main thing I really need is the location of the illumination controller and if anybody knows signal should be coming out of the I- wire, I would appreciate that as well.

[hroark7]

Turns out the whole thing was caused by a short within the in-dash clock, which overloaded the illumination control module (dimmer switch). Since the dimmer switch didn't have a good ground to send power to, it was slowly dying, and I guess it died the week that I bought my rodeo.

The whole illumination system for the clock, radio, even the gear shift, is controlled by the illumination control module. They are also all connected by two wires - a green/red wire which is a +12V signal that gets activated by turning on your headlights/parking lights from the console, and a red/green wire that adjusts the brightness of your lights. This signal has a variable voltage (I didn't actually measure it since I got it working), and the controller is able to send the unused portion of the voltage to the ground and back to the battery. When I measured the voltage of the red/green wire when the controller wasn't working, it stayed a constant 12V. If your dash lights aren't working and you are getting a constant 12V even when you adjust the dim switch, then you need to replace it. I also discovered that the ground wire attached to the control module had a .02 ohm resistance reading. I reran a new ground wire to it so the controller shouldn't blow up again.

The other problems I was experiencing were due to a short within the in-dash clock. When I cracked that sucka open, I noticed that crap job the mfgr did soldering the terminals to the circuit board. The I- wire (illumination adjustment) and the B wire (battery) were connected by solder from one terminal to the other, hidden behind the plastic housing and on the circuit board. This caused the illumination controller to have to work extra hard to make sure that the voltage on the I- wire was what it was really trying to output. I would surmise that it was also passing power from the battery to the grounding point at an alarming rate. Rather than buy a new clock, I just disconnected the I- wire from the clock, so it stays unlit. But that also solved the short.

Anyhow - hope that helps the rest of you. Oh yeah, if anybody has a good source for a rear wiper motor, please let me know. Thanks -

[rodeo02]

Interesting stuff! The clock bulb is usually one of the first thing to blow on the 1998+ rodeos. I wonder if it's got something to do with what you describe .
G/luck
Joel